Generally speaking, equipment such as atomic force microscopy (AFM) or electron microscope is commonly used to observe the geometric appearance of a substance at nano-level. When measuring using an AFM, a probe must be used to measure the geometric appearance of a sample. Such measurement process not only breaks the tip of the probe easily and takes a long time for measurement, but the measurement range of a sample is also narrower. The electron microscope, on the other hand, is free of such issues.
Taking scanning electron microscope (SEM) as an example, such microscope may be used to observe a liquid sample. When observing a liquid sample, a fluid needs to be driven to flow through a film carrying the sample to take away the metabolite of the sample, or the fluid needs to serve as a medium to add an agent required for the measurement to the sample. In such process, how to prevent the film from being damaged due to a disturbance of the fluid and how to control the temperature of the fluid flowing through the sample based on an observation requirement is a crucial factor in determining whether the liquid sample can be observed successfully. Also, the electron microscope may require an additional space and cost to implement a driving source for driving the flow of the liquid.